The present invention relates to electrodes, and more particularly, methods for manufacturing electrodes for batteries and other electrical energy storage devices.
Rechargeable batteries are accepted in a growing number of applications. Rechargeable lithium-ion batteries, for example, are prevalent in consumer electrics, power tools, electric vehicles, and aerospace applications. The success of the lithium-ion battery is at least partially attributable to a high charge density and a small loss of charge when not in use. The possibility to reduce the size of lithium-ion batteries, and other electrical energy storage devices, has generated increased interest in improvements in anode and cathode technology.
In many commercial applications, battery electrodes are formed from powder-based slurries. For example, battery electrodes can be produced from organic or aqueous-based slurries that are coated onto a metallic current collector. The slurries typically consist of active materials, conductive additives, a polymeric binder, and a solvent. The active materials are in the form of individual particles with a roughly spherical morphology. The maximum packing density for spherical morphology particles of equal diameter is 0.74 for cubic or hexagonal close packing. Further improvements in the packing density are possible by placing smaller particles into the interstitial spaces between the spherical morphology particles of equal diameter. Filling the interstitial spaces with smaller particles is difficult from a manufacturing standpoint, increases cost, increases processing and significantly increases tortuosity however.
Accordingly, there remains a continued need for an electrode with an improved packing density of an active material while mitigating the effects of tortuosity on rate performance, including electrodes for batteries and other applications.